Disposable needleless injector

ABSTRACT

A needleless hypodermic injector including a medicament containing ampule, a container of pressurized gas and a connection operatively coupling the gas to the ampule to pressurize the medicament for discharge. The ampule includes at least one rigid end wall which is provided with an opening therein which serves as a discharge orifice through which the pressurized medicament is discharged in the form of a high pressure injection stream. The opposite end of the ampule is configured to permit the medicament to be rapidly pressurized by the gas.

United States Patent 1191 Clark et a1.

[ 1 Dec. 10, 1974 DISPOSABLE NEEDLELESS INJECTOR [76] Inventors: WesleyD. Clark, 26870 Taaffee,

Los Altos Hills, Calif. 94056; Keith E. Hollenbeck, 847 Tulane Ct.,Mountain View, Calif. 94040 [22] Filed: Mar. 19, 1973 [21] Appl. No.:342,508

Related US. Application Data [63] Continuation-impart of Ser. No.186,653, Oct. 5,

1971, abandoned.

52 US. Cl. 128/173 11 51 1m.c1 ..A61m 5/30 58 Field of Search 128/17311, 173 R, 214.2,

Primary Examiner-Richard A. Gaudet Assistant Examiner-Henry J. Recla[57] ABSTRACT A needleless hypodermic injector including a medicamentcontaining ampule, a container of pressurized gas and a connectionoperatively coupling the gas to the ampule to pressurize the medicamentfor discharge. The ampule includes at least one rigid end wall which isprovided with an opening therein which serves as a discharge orificethrough which the pressurized medicament is discharged in the form of ahigh pressure injection stream. The opposite end of the am- [56] i-References Cited pul cont g d to p it th dicame t to be e 1s 1 ure erm eme n UNITED STATES PATENTS rapidly pressurized by the gas. 2,559,0917/1951 Reasenberg 141/19 2,645,223 7/1953 Lawshe et a1 128/173 11 11Claims, 3 Drawing Figures DISPOSABLE NEEDLELESS INJECTOR The presentapplication is a continuation-in-part application of parent applicationU.S. Ser. No. 186,653, filed Oct. 5, 1971 and now abandoned.

BACKGROUND OF THE INVENTION be made so inexpensively as to be entirelydisposable. Alternatively, the support structure for the ampule and gascontainer may be retained for subsequent use with replacements for theexpended ampule and/or gas container.

Another advantage of the present invention is that since the dischargeorifice forms a part of the disposable ampule, there is no need to cleanthe injector inbetween successive injections.

Another advantage of the present invention is simple and effectiveclosure of the pressurizing orifice of the medicament which alsoperforms the function of a highpressure seal when the high pressure gasis applied to the medicant chamber.

Still another advantage of the present invention is i that the extremelyshort orifice flow length imposes fore unsolved by the prior art, fullvimplementation of this injection technique has not been accomplished.For example, some prior art needleless injectors require that the samedischarge orifice be repeatedly used, in which case the orifice issubject to contamination and/or clogging. In those devices wherein thecomponent including the discharge orifice is disposable, the complexityof the orifice forming structure is such as to make that componentunduly expensive. In those prior art devices which utilize an elongatedcannula to form the discharge orifice, a pressure drop occurs over thelength of the cannula sufficient to limit the discharge velocity of theliquid and thus severely limit the depth of penetration. Anotherdisadvantage common in many of the prior art devices is that the meansof coupling the medicament containing ampule and the pressurizing sourceincludes a relatively large initially unpressured volume which, duringthe initial pressurization period, causes a substantial amount of liquidto be discharged at low pressure before the coupling volume is raised tothe required high pressure.

SUMMARY OF THE PRESENT INVENTION It is therefore an object of thepresent invention to provide a needleless injection device which isefficient, simple in structure, inexpensive and disposable.-

Another object of the present invention is to provide a disposablemedicament ampule for use in a needleless injection which has adischarge orifice that is not subject to a substantial loss of liquidpressure over its effective flow length.

Briefly, the present invention relates to a needleless hypodermicinjector including, a medicament containing ampule, a container ofpressurized gas, and a means for operatively coupling the pressurizedgas to the ampule in such a manner that the medicament is dischargedfrom the ampule in a high pressure stream. The ampule forms a medicamentcontainer having at least one rigid end wall which is provided with anopening therethrough that is of extrerr'ieilly small diameter and flowlength. This opening serves as the discharge orifice through which themedicament is forced to provide the high pressure injection stream. Theopposite end of the ampule is configured so as to sealingly close theampule, yet permit the fluid contained therein to be rapidlypressurized.

An important advantage of the present invention is that due to itsmechanical simplicity, the injector may very little pressure loss in thefluid passing therethrough and therefore enables the high pressureinjection stream to be developed using a lower gas pressure than hasheretofore been possible.

Other objects and advantages of the present invention will no doubtbecome apparent to those of ordinary skill in the art after having readthe following detailed description of certain preferred embodimentswhich are illustrated in the several figures of the drawmg.

IN THE DRAWING FIG. 1 is a schematic diagram showing a longitudinalsection taken through a needleless injection device in accordance withthe present invention.

FIG. 2 is a schematic diagram showing a longitudinal section takenthrough the embodiment illustrated in FIG. 1 during the injectionoperation.

F IG. 3 is a schematic diagram showing a longitudinal section takenthrough an alternative embodiment of the needleless injection device ofthis invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS.1 and 2 of the drawing, a simplified embodiment of a needleless injectoris illustrated in the loaded configuration (FIG. 1), and in-theinjection configuration (FIG. 2). The hypodermic device 10 includes agenerally cylindrical shaped body 12 having laterally extendingfingerpiece hooks l4 affixed to the sides thereof, an ampule 16contained within one portion of the body 12, a container 18 of highpressure gas disposed within another portion of body 12, and a cap 20which is telescopically received over the end 22 of body 12. Although asillustrated, cap 20 is intended to telescopically slide over the outersurface of body 12, it will be appreciated that end 22 and cap 20 couldbe threaded so that cap 20 could be advanced onto body 12 by rotation,rather than by the application of a compressure force F as indicated inFIG. 2. With cap 20 removed, device 10 is loaded by first insertingampule 16 into body 12,-and then inserting container 18 therebehind. Cap20 is then replaced over end 22, and device 10 is fully loaded and readyto provide an injection.

Ampule 16, in this embodiment, includes a rigid outer casing 24,preferably of stainless steel or some other suitable material which isinert with respect to the medicament 26 contained therein. At thedischarge end of ampule 16, a discharge orifice or opening 28 isprovided. At the opposite or charge end of ampule l6,

a cannula 32 is affixed having a sharply pointed end 34 for puncturinglyengaging a weakened plug 44, or soft material portion of container 18,and hence providing a flow passage 36 through which the high-pressuregases from container 18 may enter ampule 16 to pressurize the liquidmedicant contained therein.

In a preferred embodiment discharge orifice 28 is formed by aboredimensioned to provide subcutaneous-intramuscular injection for aparticular medicament at a particular pressure. Tests conducted haveshown that an opening having a diameter of approximately 0.008 inchesprovides good results as long as the length of the opening is maintainedsufficiently short to prevent too great a pressure drop therealong andthereby lowers the pressure of the pressurized medicament to a value atwhich needleless injection becomes ineffective. Tests have also shownthat a length of less than about 0.024 inches is eminantly suitable andthat the effectiveness of the needleless injection increases withdecrease in the bore length because of the greater retained pressure ofthe medicament. The term dimensioned for needleless injection, as usedin the appended claims in connection with the discharge orifice 28,means a bore having a diameter and a length combination which providesan acceptable subcutaneousintramuscular injection of the particularmedicament contained in capsule 16 when pressurized by the gas incontainer 18.

It has also been found that satisfactory subcutaneousintramuscularinjection can be had with somewhat different combination between openingdiameter and opening length. The larger the opening diameter, the longermay be the opening length without suffering an unacceptably largepressure drop. The term ,dimensioned for lack of medicament leakage asused in the appended claims in connection with the discharge orifice 28,means a bore which is dimensioned for needleless injection, as this termhas been defined above, and in which the diameter is further selectedsufficiently small to prevent normal medicament leakage through the borewhen the medicament is not pressurized. A bore diameter of 0.008 inchesfor a medicament having an average viscosity has been found to meet thiscriteria also.

Selection of gas pressure for pressurizing the medicament depends on thedesired depth of the subcutaneous-intramuscular injection. For example,medicaments pressurized to 800-1 100 psi usually provide intradermalpenetration and medicaments pressurized to 1,700 psi or above usuallyprovide intramuscular penetration. Medicants pressurized between 1,100and 1,700 psi provide subcutaneous penetration.

Because of the extremely small size of orifice 28 no seal is normallyrequired to prevent leakage of the medicament therethrough within theusual range of medicament viscosities. However, where an injectionliquid of extremely low viscosity is to be contained within ampule 16,it may be advistable to provide a thin plastic or wax coating over theend 30 to prevent leakage, such coating being easily pierced by theliquid medicament as it is pressurized during the injection operation.

To prevent leakage of the medicament through cannula 32, a cap 48 isprovided which caps the cannula.

Cap 48 may be simply a cylindrical plug made out of to plug the cannularpassage 36 and provides an effective seal. It should also be noted thatcap 48 also provides a high pressure seal between the outer shoulder ofcartridge 18 facing the cannula and ampule 16 as the pressurizedcatrdige is moved against the ampule for pressurizing the medicament.

In operation, the device is held in one hand with two fingers hookedabout the fingerhoods 14. As cap 20 is squeezed into the heel of thehand, cap 20 moves telescopically over end 22 of body 12, thereby movingcon tainer l8 leftwardly into engagement with cannula 32. As cannula 32pierces the weakened plug 44 and extends into container 18, thehigh-pressure gases rushing through passageway 36 to begin the initialpressurization of fluid 26. The pressure causes the liquid 26 at theright-most end of ampule 16 to be forced with the result being thatliquid 26 is more or less uniformly pressurized and moved in a column,as indicated at 46 in FIG. 2, for discharge through opening 28. Cap 48,moved inwardly along the cannula by the shoulder of container 18 alsoprovides a seal for preventing excess leakage of gases around cannula32.

. Once the injection is complete, the entire device may be disposed of,or ampule l6 and container 18 may be removed from body '12 and replacedwith fully charged elements so that the body 12 and cap 20 can bereused. Since the forces exerted on body 12 are of relatively smallmagnitude, it is contemplated that by using inexpensive plastic or nylonmaterials, the entire hypodermic device may be economically madedisposable.

Turning now to FIG. 3 of the drawing, an alternative embodiment of aneedleless hypodermic injector is illustrated at 130. This embodimentincludes a medicament containing unit 132, a high pressure gas source134, and a valve body 136 for selectively coupling unit 132 to source134. Ampule 132 may be configured in a manner similar to the previouslydescribed ampules, except that in this embodiment it has threads tofacilitate its attachment to valve body 136. j

Valve body 136 is configured to include a threaded coupling 152 formating with the threaded end of unit 132, a threaded coupling 154 formating with the threaded discharge end 156 of gas source 134, anopening158 for receiving the initially capped cannula of ampule 132 in whichcap 48 is pushed inwardly to provide a seal against unit 130, a cannula160 for piercing the discharge end 162 of gas source 134, and arotatable valve member 166 having a passage 168 extending more or lesstransversely therethrough. A handle 169 is affixed to one end of member166.

Note that passage 168 is enlarged at the end 170 so that as member 166is rotated clockwise from the loading position to the injectionposition, the end 170 of passage-.166 communicates with source 134slightly before the end 172 communicates with opening 158. This allowsthe transitional pressurization of passage 168 to occur before ampule132 is subjected to pressurization. Thus, the slow pressurizationdisadvantages of the prior art mentioned above are circumvented.

In operation, with source 134 screwed into the operative positionillustrated in FIG. 3, the medicament containing unit 132 is screwedinto place as indicated. End 144 is then pressed against the surface tobe injected and handle 167 is rotated clockwise into the injectionposition illustrated in FIG. 3 and left in that position until all ofthe medicament is discharged from the ampule 132. When the injection iscompleted, actuator 168 is rotated counterclockwise back into theloading position.

Even though source 134 may only contain sufficient pressurizing gas forone injection, it is to be understood that a larger source can likewisebe utilized together with a valve which provides a measured amount ofpressurizing gas to the medicament chamber. In this manner, severaldisposable ampules 132 may be used with a single pressurization source.

It is to be noted that in each of the above described embodiments, thedischarge orifice'forms a part of the disposable component, thusobviating one of the most troublesome problems associated with the priorart devices; namely that of cleaning and maintaining the dischargeorifice clear of obstruction. Furthermore, since the discharge orificeis formed in a thin wall of the disposable ampule, its length can bemade much shorter than would be possible in the case of a device havinga re-useable orifice, and thus the pressure drop sulfered by the liquidin passing through the discharge orifice is kept to a minimal loss. Notealsothat in the case of each of the above disclosed embodiments, theinitially unpressurized volume coupling the gas source to the ampule isheld to an absolute minimum so that maximum pressurization of the ampuleis obtained almost instantaneously, thereby insuring that a full dosageof medicament is injected.

Whereas the invention has been described above in terms of severalsmplified preferred embodiments, it is to be understood that thedisclosure is intended to be illustrative only, and is in no way to betaken as limiting. Accordingly, it isintended that the claims beinterpreted as covering all modifications of the invention which fallwithin the true spirit and scope of the invention.

What is claimed is: 1. A needleless hypodermic injector, comprising: anampule filled with a liquid medicant to be injected and including, apressurizing end portion for receiving a charge of pressurizing gas, anda rigid discharge end portion for placing directly into contact with theskin where the injection is to be made which has a substantially uniformdiameter bore extending therethrough which is dimensioned for needlelessinjection; a container of pressurized gas; and means for pressurizingsaid medicant directly with a charge of said pressurizing gas to form amedicantgas mixture which is expelled through said bore for needlelessinjection. 2. A needleless hypodermic injector in accordance with claim1 in which said container of pressurized gas includes a puncturablemembrane and said pressurizing 7 end portion of said ampule includes apuncturing means for puncturing said membrane.

3. A needleless hypodermic injector in accordance with claim 2 whichfurther includes a resilient capping means disposed upon said puncturingmeans for sealing the pressurizing end portion of said ampule.

4. A needleless hypodermic injector in accordance with claim 3 in whichsaid capping means is configured for engagement by the area of saidcontainer immediately. surrounding the opening generated upon punc tureof said membrane by said puncturing means, said capping means includinga puncturable end portion for puncturing by said puncturing means.

5. A needleless hypodermic injector in accordance with claim 4 in whichsaid capping means is slidable along said puncturing means and forms asealing contact between said ampule and container during pressurizationof said medicant.

6. A needleless hypodermic injector as recited in claim 1 which furtherincludes an elongated casing forming a chamber having openings at bothends, said ampule being disposed within said chamber with said dischargeend portion extending through one of said openings, and said containerbeing slidably disposed within said chamber opposite said pressurizingend portion, and said means for pressurizing said medicant having acannula affixed to said pressurizing end portion for puncturing saidcontainer.

7. A needleless hypodermic injector in accordance with claim 6 furtherincluding a casing cap slidingly disposed over the other of saidopenings of said casing and in contact with the said container.

8. A needleless hypodermic injector in accordance with claim 7 furtherincluding finger hold means integral connected to said casing wherebysqueezing the casing cap with the heel of the hand against said casingwith fingers engaging said finger hold means pressurizes said medicant.

9. A needleless hypodermic injector as recited in claim 1 in which saidmeans for pressurizing includes a valve having a valve element movablebetween an open and a closed position.

10. A needleless hypodermic injector in accordance with claim 6 whichfurther includes a capping means engaging the tip of said cannula forsealing the pressurizing end portion of said ampule.

11. A needleless hypodermic injector in accordance with claim 10 inwhich said capping means is configured for sliding engagement along theouter surface of said cannula and includes a puncturable end portion forpuncturing by the tip of said cannula when said container is movedtowards said ampule for pressurizing said medicant.

1. A needleless hypodermic injector, comprising: an ampule filled with aliquid medicant to be injected and including, a pressurizing end portionfor receiving a charge of pressurizing gas, and a rigid discharge endportion for placing directly into contact with the skin where theinjection is to be made which has a substantially uniform diameter boreextending therethrough which is dimensioned for needleless injection; acontainer of pressurized gas; and means for pressurizing said medicantdirectly with a charge of said pressurizing gas to form a medicant-gasmixture which is expelled through said bore for needleless injection. 2.A needleless hypodermic injector in accordance with claim 1 in whichsaid container of pressurized gas includes a puncturable membrane andsaid pressurizing end portion of said ampule includes a puncturing meansfor puncturing said membrane.
 3. A needleless hypodermic injector inaccordance with claim 2 which further includes a resilient capping meansdisposed upon said puncturing means for sealing the pressurizing endportion of said ampule.
 4. A needleless hypodermic injector inaccordance with claim 3 in which said capping means is configured forengagement by the area of said container immediately surrounding theopening generated upon puncture of said membrane by said puncturingmeans, said capping means including a puncturable end portion forpuncturing by said puncturing means.
 5. A needleless hypodermic injectorin accordance with claim 4 in which said capping means is slidable alongsaid puncturing means and forms a sealing contact between said ampuleand container during pressurization of said medicant.
 6. A needlelesshypodermic injector as recited in claim 1 which further includes anelongated casing forming a chamber having openings at both ends, saidampule being disposed within said chamber with said discharge endportion extending through one of said openings, and said container beingslidably disposed within said chamber opposite said pressurizing endportion, and said means for pressurizing said medicant having a cannulaaffixed to said pressurizing end portion for puncturing said container.7. A needleless hypodermic injector in accordance with claim 6 furtherincluding a casing cap slidingly disposed over the other of saidopenings of said casing and in contact with the said container.
 8. Aneedleless hypodermic injector in accordance with claim 7 furtherincluding finger hold means integral connected to said casing wherebysqueezing the casing cap with the heel of the hand against said casingwith fingers engaging said finger hold means pressurizes said medicant.9. A needleless hypodermic injector as recited in claim 1 in which saidmeans for pressurizing includes a valve having a valve element movablebetween an open and a closed position.
 10. A needleless hypodermicinjector in accordance with claim 6 which further includes a cappingmeans engaging the tip of said cannula for sealing the pressurizing endportion of said ampule.
 11. A needleless hypodermic injector inaccordance with claim 10 in which said capping means is configured forsliding engagement along the outer surface of said cannula and includesa puncturable end portion for puncturing by the tip of said cannula whensaid container is moved towards said ampule for pressurizing saidmedicant.